Expanded foam solution and thermosetting expanded foam having excellent flame retardancy using the same

ABSTRACT

The present disclosure relates to an expanded foam solution for forming a thermosetting expanded foam having excellent flame retardancy produced using the same. According to the present disclosure, nanoclay is mixed with a polyol-based compound using ultrasonic waves, an isocyanate-based compound is added, and a trimerization catalyst or an isocyanurate compound is mixed with the polyol-based compound so that an isocyanurate structure is formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 17/225,742, filed on Apr. 8, 2021, which claims the priority ofcontinuation-in-part of PCT/KR2019/013393, filed Oct. 11, 2019, whichfurther claims priority to KR10-2018-0121633, filed Oct. 12, 2018, theentire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an expanded foam solution and athermosetting expanded foam produced using the same, and moreparticularly, to the thermosetting foam having an excellent flameretardancy prepared by the method including: in order to provide apolyurethane foam for construction having excellent flame retardancy;mixing nanoclay with a polyol-based compound using ultrasonic waves;adding an isocyanate-based compound thereto; and mixing a trimerizationcatalyst or an isocyanurate compound with the polyol-based compound toform an isocyanurate structure, and to a thermosetting expanded foamproduced using the same.

BACKGROUND ART

The Ministry of Land, Infrastructure and Transport of the Republic ofKorea significantly strengthened the fire safety standards of buildingfinishing materials by revising the ‘rules on standards forevacuation/fire protection structures of buildings, etc.’, and theserevised rules have taken effect from April 2016. In particular, hugelosses of both life and property have occurred due to large fireaccidents that have occurred recently, and for this reason,heat-insulating materials having excellent fire safety and heatinsulation properties have attracted attention. However, in spite ofthis demand, technology for producing heat-insulating materials havingexcellent flame retardancy and the supply of products obtained using thesame remains insufficient. Materials that are used as heat-insulatingmaterials for buildings include expanded polystyrene foam (EPS), glassfiber, phenolic foam, polyurethane (hereinafter referred to as “PU”)foam and polyisocyanurate (hereinafter referred to as “PIR”) foam. EPSfoam is the most common insulation material, but has been pointed out asone of the major causes of large fire accidents because it easilycatches fire. Glass fiber has low heat-insulation properties and isclassified as a material harmful to the human body, and thus its use islimited. Phenolic foam has been in the spotlight as an organicheat-insulating material having excellent heat insulation and flameretardant performance, but has problems in that, when it absorbsmoisture, the heat insulation property thereof extremely deteriorates,and the surrounding construction subsidiary materials are corroded dueto the generation of acid. In addition, phenolic foam has lowworkability due to its poor adhesion to the adherend surface of aconstruction material. PU foam and PIR foam have various excellentproperties such as heat insulation performance, water resistance,processability and workability, but have a problem in that they haverelatively low flame retardancy, and thus their function of preventingthe spread of fire in a fire situation is relatively poor.

In the PU foam- and PIR foam-related industry, extensive efforts haverecently been made to improve flame retardant performance which is theshortcoming of these foams. There are various methods of makingmaterials flame-retardant. One of these methods is the application ofexpansion agents that induce expansion by high temperature to form abarrier against the flame in a fire situation. The expansion agents maybe divided into an organic expansion agent and an inorganic expansionagent. The organic expansion agent has a low specific gravity and hashigh processability due to its high compatibility with organic materialssuch as PU or PIR. However, the organic expansion agent has poor flameretardant performance because it is an organic material that easilycatches fire. The inorganic expansion agent has excellent flameretardant performance. However, the inorganic expansion agent has highspecific gravity, and is likely to undergo phase separation such asprecipitation due to its high incompatibility with an organic material.In addition, although the inorganic expansion agent blocks the spread ofa flame by expansion in a fire situation, this blocking is temporary,and if the flame is continuously applied, the foam collapses due tomelting, and thus the flame retardant performance thereof is degradedagain. Another method of making materials flame-retardant is a method ofadding flame retardants. Organic flame retardants have a disadvantage inthat they generate gases harmful to the human body when catching fire.Inorganic flame retardants have a problem in that the mechanical andphysical properties thereof are degraded. In addition, the introductionof these flame retardants alone is very insufficient to satisfy currentrequirements for the fire safety of building finishing materials.

In order to solve the above problems, it is important to maximize flameretardant performance by addition of flame retardants or flame retardantadditives while maintaining mechanical and physical properties. Inrecent years, nanocomposite materials containing various nanoparticleshave been developed, and particularly, research results have beenreported that proper dispersion of nanoclay in these materials improvesflame retardant performance to a certain level or more. Regarding flameretardant properties which are achieved through nanoclay, nanoclayparticles having a large aspect ratio, obtained through nanoclayintercalation and exfoliation, exert their performance through an actionthat blocks heat and effectively prevents fire spread in a firesituation by increasing their contact area with these resins.

However, if the techniques of effectively dispersing, intercalating andexfoliating nanoclay in these materials are not completely accomplished,the nanoclay is nothing more than a simple inorganic flame retardant,and can merely cause the adverse effect of lowering mechanical andphysical performance, rather than improving flame retardant performance.In addition, only when the material itself as a matrix has a certaindegree of flame retardancy, the performance thereof is maximized. Someforeign companies and researchers have attempted to improve flameretardant performance by dispersing nanoclay in a PU-based matrix, butthis attempt did not lead to mass production because the effect thereofwas remarkably low for the added process cost. In addition, in thiscase, situations that end only with research were often presented.

The nanoclay contains components, including silicon, aluminum, magnesiumand oxygen, and has a basic layered structure composed of a silicatetrahedron and an alumina octahedron, which are present at a ratio of1:1 or 1:2. Each nanoclay layer has a thickness of 1 to 10 nm and alength of 30 to 1000 nm, and the spacing between nanoclay layers is afew Å (1 Å=10 nm).

Dispersion methods for intercalating a resin into the interlayer spaceof the nanoclay and exfoliating the nanoclay include a solutiondispersion method, a melting method, and an ultrasonic method. Thesolution dispersion method is a method of inducing a resin to beintercalated into the interlayer space of the nanoclay through stirringwhen the interlayer spacing of the nanoclay is expanded while thenanoclay is swollen in a liquid phase. The problem at this time is that,since the nanoclay is aggregated by the Van der Waals attraction actingbetween the nanoclay layers, the intercalation efficiency is very lowand exfoliation of the nanoclay is more difficult than theintercalation. The melting method has a limitation that a thermoplasticresin capable of melting at a processing temperature of 200° C. or lessshould be used, and it is difficult to apply the melting method tothermosetting foam. The ultrasonic method is a method of maximallyexpanding the interlayer space of nanoclay through application of acertain level or higher of ultrasonic waves, intercalating a resin intothe interlayer space and exfoliating the nanoclay. The efficiency ofintercalation into the nanoclay interlayer space or exfoliation of thenanoclay layers changes depending on the ultrasonic intensity, and thuscontrol is absolutely necessary.

The effect appears only when the resin is liquid and the viscositythereof does exceed a certain level. Nanoclay contains a minimum amountof moisture even after it is organically modified. Therefore, the resinshould not be reactive with moisture, and if it is reactive, it maycause irreversible changes over time, thereby degrading physicalproperties.

In Korean Patent Application Nos. 10-2017-0085232, 10-2011-0031592,10-2010-0082116, 10-2007-0122780, 10-2002-0083028, and 10-2002-0083066,the solution dispersion method is used to intercalate a resin into theinterlayer space of nanoclay. As mentioned above, since the nanoclay isaggregated by the Van der Waals attraction between the nanoclay layers,the intercalation efficiency of the resin is low, and exfoliation of thenanoclay is more difficult than the intercalation. Thus, the effect isnot sufficient. In Korean Patent Application Nos. 10-2007-0140846,10-2005-0012348 and 10-2005-0000687, nanoclay is mixed with anisocyanate-based resin, and intercalation of the resin is induced byapplying ultrasonic waves. However, since the isocyanate-based resinirreversibly reacts even with a very small amount of moisture containedin the nanoclay, changes over time occur. Even if the nanoclay is dried,moisture cannot be completely removed therefrom, and even if it isassumed that the nanoclay is completely dried, intercalation of theresin into the nanoclay interlayer space by ultrasonic waves alone isdifficult due to aggregation of the nanoclay. In addition, the purposeis different from the present disclosure aimed at maximizing flameretardant performance using nanoclay.

Korean Patent Application Publication No. 10-2015-0063990 discloses athermosetting foam having improved flame retardancy, which includes anisocyanurate structure using a trimerization catalyst. Although thethermosetting foam is an excellent base material, the effect thereof isdecreased rather than increased, because the nanoclay is applied by asolution dispersion method based on stirring.

Meanwhile, technology of making organic heat-insulating materialsflame-retardant is very important in view of the fact that regulationson fire safety are increasingly being strengthened. A heat-insulatingmaterial consisting of a single material that has a total weight loss of6.5 g or less for 5 minutes after the start of the burning testaccording to ISO 5660-1 is hard to find anywhere.

DISCLOSURE Technical Problem

The present disclosure has been made in order to solve theabove-described problems, and an object of the present disclosure is toprovide a thermosetting expanded foam solution for forming a foamprepared by the method including mixing nanoclay with a polyol-basedcompound using ultrasonic waves, adding an isocyanate-based compoundthereto, allowing the polyol-based compound and the isocyanate-basedcompound to react in the expanded interlayer space of the nanoclay sothat the expanded interlayer space of the nanoclay is further expandeddue to the structure resulting from the reaction so that completeexfoliation of the nanoclay occurs, and a thermosetting expanded foamhaving an excellent flame retardancy produced using the expanded foamsolution.

Technical Solution

As a means for achieving the above object,

an expanded foam solution for forming a foam and a thermosettingexpanded foam having an excellent flame retardancy using the sameaccording to the present disclosure are configured as follows.

The present invention provides an expanded foam solution for forming athermosetting expanded foam having excellent flame retardancy, theexpanded foam solution including: at least one polyol-based compoundselected from among polyester polyol and polyether polyol; a mixtureincluding at least one of a trimerization catalyst and an isocyanuratecompound, water, a surfactant, a flame retardant, and a catalyst; and amixture solution composed of the compound, the mixture and nanoclay andobtained by treating a nanoclay-polyol interlayer compound, whichcontains the nanoclay in an amount of 1 to 10 wt % based on 100 wt % ofthe mixture solution, with ultrasonic waves having an intensity of 200or 3,000 W at a frequency of 20 kHz or with a high pressure of 1,000 to3,000 bar; and a foaming agent.

The present invention also provides a thermosetting expanded foamobtained by curing the expanded foam solution with a curing agent.

More detailed, in the expanded foam solution for forming a foam and athermosetting expanded foam having excellent flame retardancy obtainedby curing the expanded foam solution, the mixture solution has aviscosity of 5,000 cps or less, the nanoclay has a water content of 0.5to 10%, a true density of 1.5 to 3 g/cm3 and an average particlediameter (d50) of 30 μm or less. In addition, the nanoclay-polyolinterlayer compound is formed by intercalation of the compound and themixture into the expanded interlayer space of the nanoclay and has atleast one structure selected from a urethane structure, a urea structureand an isocyanurate structure, and the molecular weight and volume ofthe nanoclay-polyol interlayer compound increase rapidly due to the atleast one structure, so that the expanded interlayer space of thenanoclay is further expanded and exfoliation of the nanoclay occurs.

More specifically, a method for producing the expanded foam solution forforming a thermosetting expanded foam having excellent flame retardancyand for producing the foam may include steps of:

a method for producing a thermosetting foam having excellent flameretardancy according to the present disclosure includes steps of:

(1) preparing a polyol-based compound mixed with a trimerizationcatalyst or an isocyanurate compound;

(2) preparing a mixture containing the polyol-based compound, asurfactant, a flame retardant and a catalyst;

(3) preparing a mixture solution by adding nanoclay to the mixture;

(4) applying ultrasonic waves or high pressure to the mixture solutionto expand the interlayer space of the nanoclay and to allow the mixturein the mixture solution to be intercalated into the expanded interlayerspace of the nanoclay;

(5) adding a foaming agent to the mixture resulting from step (4);

(6) adding an isocyanate-based compound to the mixture resulting fromstep (5);

(7) subjecting the polyol-based compound and the isocyanate-basedcompound to an in-situ chain reaction in the expanded interlayer spaceof the nanoclay; and

(8) allowing exfoliation of the nanoclay to occur by further expansionof the expanded interlayer space of the nanoclay through rapid increasesin molecular weight and volume due to a urethane structure, a ureastructure and an isocyanurate structure, which are produced as a resultof step (7).

In addition, the polyol-based compound may be polyether polyol orpolyester polyol.

In addition, the trimerization catalyst may include a tertiary amine, atriazine and a metal salt trimerization catalyst, the metal salttrimerization catalyst may be an alkali metal salt of an organiccarboxylic acid, the organic carboxylic acid may be acetic acid or2-ethylhexanoic acid, and the alkali metal may be potassium or sodium.

In addition, the isocyanurate compound may be at least any one selectedfrom the group consisting of triallyl isocyanurate,tris(2,3-epoxypropyl)isocyanurate, tris(hydroxyethyl)isocyanurate,tris(2-carboxyethyl)isocyanurate,tris[3-(trimethoxy)propyl]isocyanurate, and tris [2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

In addition, the nanoclay may have a water content of 0.5 to 10%, a truedensity of 1.5 to 3 g/cm³, and an average particle diameter (d50) of 30μm or less.

In addition, the nanoclay may be contained in an amount of 1 to 10 wt %based on 100 wt % of the mixture solution.

In addition, the nanoclay may be at least any one selected from thegroup consisting of montmorillonite, bentonite, hectorite, saponite,beidelite, nontronite, mica, vermiculite, carnemite, magadiite,kenyaite, kaolinite, smectite, illite, chlorite, muscovite,pyrophyllite, antigorite, sepiolite, imogolite, sobokite, nacrite,anauxite, sericite, ledikite, and combinations thereof.

In addition, the nanoclay may be at least any one selected from thegroup consisting of: hydrophilic nanoclay modified by substitution withan alkyl ammonium or alkyl phosphonium ion treated with a Na⁺ ion, aCa⁺⁺ ion or an acid or having an end hydroxyl group (—OH), in theinterlayer space thereof; hydrophobic nanoclay organically modified bysubstitution with a hydrophobic alkyl ammonium or alkyl phosphonium ion;and a combination of the hydrophilic nanoclay and the hydrophobicnanoclay.

In addition, the nanoclay may be used in combination with CNTs.

In addition, the interlayer space of the nanoclay may include oneselected from the group consisting of silane coupling agents andcombinations thereof.

In addition, the silane coupling agent may be at least any one selectedfrom the group consisting of aminopropyltrimethoxysilane,3-(2-aminoethyl)aminopropylmethyldimethoxysilane,(3-trimethoxysilylpropyl)diethyleneamine,bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane,glycidoxypropyltrimethoxysilane, and bis(trimethoxysilyl)ethane.

In addition, the mixture solution may have a viscosity of 5000 cps orless.

In addition, the ultrasonic waves that are applied in step (4) may havean intensity of 200 to 3,000 W at a frequency of 20 kHZ.

In addition, the high pressure in step (4) may be a pressure of 1000 to3,000 bar, which is applied through a high-pressure homogenizer.

In addition, step (5) may be performed at a temperature below theboiling point of the foaming agent.

In addition, the isocyanate-based compound may be selected from amongm-MDI (monomeric-methylene diisocyanate), p-MDI (polymeric-methylenediisocyanate), TDI (toluene diisocyanate), derivatives thereof ormixtures thereof.

In addition, the ratio of the weight of the isocyanate-based compound,which is added in step (6), relative to the weight of the mixtureresulting from step (5), may be 0.65 to 3.0.

In addition, the thermosetting foam may have a density of 35 kg/m³ to 40kg/m³, and may be hard, soft or semi-hard foam.

In addition, after a specimen of the thermosetting foam is burned for 5minutes according to an ISO 5660-1 test method, the specimen may beincreased in height by 3 mm to 10 mm due to expansion of char, and thetotal weight loss thereof may not exceed 5.0 g to 6.5 g while theexpanded state of the char that increased in height is maintained.

The thermosetting foam having excellent flame retardancy according tothe present disclosure may be produced by any one of the methods forproducing a thermosetting foam having excellent flame retardancy.Advantageous Effects

According to the embodiments, after a specimen of the thermosetting foamhaving excellent flame retardancy according to the present disclosure issubjected to a burning test for 5 minutes according to ISO 5660-1, thespecimen may be increased in height by 3 mm to 10 mm due to expansion ofchar, and the total weight loss thereof may not exceed 5.0 g to 6.5 gwhile the expanded state of the char that increased in height ismaintained, suggesting that the thermosetting foam has excellent flameretardancy.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A-1D are schematic views showing the mechanism by which atrimerization catalyst and a polyol are intercalated into the interlayerspace of nanoclay and the nanoclay is exfoliated, in the presentdisclosure.

FIG. 2 is a graph showing the X-ray diffraction pattern of athermosetting foam according to the present disclosure.

FIG. 3 is a view showing an in-situ chain reaction mechanism in theproduction of the thermosetting foam according to the presentdisclosure.

FIG. 4 is a view showing that the height of the thermoplastic foamaccording to the present disclosure is increased due to expansion afterthe start of burning.

MODE FOR INVENTION

Hereinafter, a thermosetting expanded foam solution for forming a foamhaving excellent flame retardancy and an expanded foam using the sameaccording to the present disclosure will be described in further detailwith reference to the accompanying drawings.

An expanded foam solution for forming a foam and an expanded foam havingexcellent flame retardancy using the same according to the presentinvention are configured as follows.

The present invention provides an expanded foam solution for forming athermosetting expanded foam having excellent flame retardancy, theexpanded foam solution including: at least one polyol-based compoundselected from among polyester polyol and polyether polyol; a mixtureincluding at least one of a trimerization catalyst and an isocyanuratecompound, water, a surfactant, a flame retardant, and a catalyst; and amixture solution composed of the compound, the mixture and nanoclay andobtained by treating a nanoclay-polyol interlayer compound, whichcontains the nanoclay in an amount of 1 to 10 wt % based on 100 wt % ofthe mixture solution, with ultrasonic waves having an intensity of 200or 3,000 W at a frequency of 20 kHz or with a high pressure of 1,000 to3,000 bar; and a foaming agent.

The present invention also provides a thermosetting expanded foamobtained by curing the expanded foam solution with a curing agent.

In the expanded foam solution for forming a thermosetting expanded foamhaving excellent flame retardancy and an expanded foam obtained bycuring the expanded foam solution, the mixture solution has a viscosityof 5,000 cps or less, the nanoclay has a water content of 0.5 to 10%, atrue density of 1.5 to 3 g/cm³ and an average particle diameter (d50) of30 μm or less. In addition, the nanoclay-polyol interlayer compound isformed by intercalation of the compound and the mixture into theexpanded interlayer space of the nanoclay and has at least one structureselected from a urethane structure, a urea structure and an isocyanuratestructure, and the molecular weight and volume of the nanoclay-polyolinterlayer compound increase rapidly due to the at least one structure,so that the expanded interlayer space of the nanoclay is furtherexpanded and exfoliation of the nanoclay occurs. Further, athermosetting expanded foam obtained by curing the expanded foamsolution with a curing agent.

The present disclosure is directed to a method for producing athermosetting foam having excellent flame retardancy, the methodincluding steps of: (1) preparing a polyol-based compound mixed with atrimerization catalyst or an isocyanurate compound;

(2) preparing a mixture containing the polyol-based compound, asurfactant, a flame retardant and a catalyst;

(3) preparing a mixture solution by adding nanoclay to the mixture;

(4) applying ultrasonic waves or high pressure to the mixture solutionto expand the interlayer space of the nanoclay and to allow the mixturein the mixture solution to be intercalated into the expanded interlayerspace of the nanoclay;

(5) adding a foaming agent to the mixture resulting from step (4);

(6) adding an isocyanate-based compound to the mixture resulting fromstep (5);

(7) subjecting the polyol-based compound and the isocyanate-basedcompound to an in-situ chain reaction in the expanded interlayer spaceof the nanoclay; and

(8) allowing exfoliation of the nanoclay to occur by further expansionof the expanded interlayer space of the nanoclay through rapid increasesin molecular weight and volume due to a urethane structure, a ureastructure and an isocyanurate structure, which are produced as a resultof step (7).

The method for producing a thermosetting foam having excellent flameretardancy according to the present disclosure will now be described inmore detail with reference toFIGS. 1A-1D.

First, in step (1), a polyol-based compound mixed with a trimerizationcatalyst or an isocyanurate compound is prepared.

The polyol-based compound may be polyether polyol or polyester polyol.

The polyether polyol may be produced by polymerizing at least oneselected from the group consisting of ethylene glycol, 1,2-propaneglycol, 1,3-propylene glycol, butylene glycol, 1,6-hexanediol,1,8-octanediol, neopentyl glycol, 2-methyl-1,3-propanediol, glycerol,trimethylolpropane, 1,2,3-hexanetriol, 1,2,4-butanetriol,trimethylolmethane, pentaerythritol, diethylene glycol, triethyleneglycol, polyethylene glycol, tripropylene glycol, polypropylene glycol,dibutylene glycol, polybutylene glycol, sorbitol, sucrose, hydroquinone,resorcinol, catechol, and bisphenol, with ethylene oxide, propyleneoxide, or a mixture thereof.

The polyester polyol may be produced by polymerizing phthalic anhydrideor adipic acid with ethylene oxide, propylene oxide, or a mixturethereof.

In order to form an isocyanurate structure using the polyol-basedcompound of the present disclosure, a trimerization catalyst is mixedwith the polyol-based compound, or an isocyanurate compound is mixedwith the polyol-based compound.

The trimerization catalyst that is mixed with the polyol-based compoundinduces a metal salt to act as an activator so that an isocyanatecompound itself participates in an isocyanurate reaction. Thetrimerization catalyst may be composed of a tertiary amine, a triazineand a metal salt trimerization catalyst. The metal salt trimerizationcatalyst may be an alkali metal salt of an organic carboxylic acid, theorganic carboxylic acid in the alkali metal salt of the organiccarboxylic acid may be acetic acid or 2-ethylhexanoic acid, and thealkali metal may be potassium or sodium.

The isocyanuate compound that is mixed with the polyol-based compoundmay be at least any one selected from among triallyl isocyanurate,tris(2,3-epoxypropyl)isocyanurate, tris(hydroxyethyl)isocyanurate,tris(2-carboxyethyl)isocyanurate,tris[3-(trimethoxy)propyl]isocyanurate, andtris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

In step (2), a mixture is prepared by mixing a surfactant, a flameretardant, a catalyst and water with the polyol-based compound mixedwith the trimerization catalyst or the isocyanurate compound, preparedin step (1).

The surfactant serves to control the surface tension of foam cellsduring cell formation, thereby preventing the size of the foam cellsfrom excessively increasing and stabilizing the formation of the foamcells. Surfactants are divided into a silicone-based surfactant and anon-silicone-based surfactant. The silicone-based surfactant may be asilicone-based copolymer or any compound containing or combined with thesame, and the non-silicone-based surfactant may be dinonyl phenol,methyl glucoside, methyl propanediol, vinyl ether maleic acid, vegetableoil, or any surfactant containing or combined with the same.

The flame retardant may be at least one selected from the groupconsisting of a phosphorus-based flame retardant, a metal hydrate-basedflame retardant, a halogen-based flame retardant, an inorganic flameretardant, a flame retardant aid, and mixtures thereof. Thephosphorus-based flame retardant includes at least one selected from thegroup consisting of triphenyl phosphate, cresyl diphenyl phosphate,isopropylphenyl diphenyl phosphate, and mixtures thereof. In addition,the halogen-based flame retardant includes decabromodiphenyl oxide oroctabromodiphenyl oxide, and the flame retardant aid includes antimonytrioxide.

The catalyst serves to control the reaction time, and may be at leastone selected from the group consisting of dimethylethanolamine (DMEA),dimethylcyclohexylamine (DMCHA), pentamethylenediethylene triamine(PMETA), tetramethylene hexyl diamine (TMHDA), and mixtures thereof.

In step (3), a mixture solution is prepared by mixing the mixture ofstep (2) with nanoclay (FIG. 1A).

Although the nanoclay may be used in a mixture with an isocyanate-basedcompound, the isocyanate-based compound reacts irreversibly even with avery small amount of moisture, and hence mixing of the isocyanate-basedcompound with nanoclay having hydrophilicity is not preferable becauseit causes the solution to deteriorate or change over time, resulting indeterioration in the properties of the final product. In addition, evenif it is assumed that the nanoclay is completely dried, the nanoclayparticles are aggregated by water during the drying process, and hencethe dispersion efficiency of the particles in the subsequent process ofapplying ultrasonic waves or high pressure decreases. In fact, even ifthe hydrophilic nanoclay is organically modified, the originalhydrophilic component of the nanoclay cannot be completely removed. Forthis reason, it is preferable to mix the nanoclay with the polyol-basedcompound-containing mixture of step (2).

The water content of the nanoclay is preferably maintained at 0.5 to10%. The nanoclay has the property of swelling with water, and thus ifthe water content of the nanoclay is less than 0.5%, the nanoclayparticles become difficult to disperse, due to aggregation between theparticles.

On the other hand, if the water content is more than 10%, the watercontent of the polyol-based compound that is mixed with the nanoclayincreases, and the physical properties thereof change after the reactionwith the isocyanate-based compound.

The true density of the nanoclay is preferably maintained at 1.5 to 3g/cm^(3.) If the true density is less than 1.5 g/cm³, the specificsurface area may increase, and thus the nanoclay may easily absorbmoisture, and if the true density is more than 3 g/cm³, the load of thenanoclay may increase, and thus the nanoclay may precipitate even afterdispersion with the polyol-based compound, resulting in a change in thephysical properties thereof.

The average particle diameter (d50) of the nanoclay is preferably 30 μmor less. If the average particle diameter is larger than 30 μm, thedensity of the nanoclay may increase and the nanoclay may precipitatedue to the load thereof.

In addition, the nanoclay may be contained in an amount of 1 to 10 wt %based on 100 wt % of the mixture solution containing the mixture and thenanoclay. If the nanoclay is contained in an amount of less than 1 wt %,the effect of improving physical properties may not be achieved, and ifthe nanoclay is contained in an amount of more than 10 wt %, thedispersion efficiency of the nanoclay may be lowered, resulting indeterioration in physical properties.

The nanoclay is at least any one selected from the group consisting ofmontmorillonite, bentonite, hectorite, saponite, beidelite, nontronite,mica, vermiculite, carnemite, magadiite, kenyaite, kaolinite, smectite,illite, chlorite, muscovite, pyrophyllite, antigorite, sepiolite,imogolite, sobokite, nacrite, anauxite, sericite, ledikite, andcombinations thereof.

The nanoclay may be used after organic modification. That is, theinterlayer cation of the nanoclay may be ion-exchanged with an alkylammonium or alkyl phosphonium ion. Depending on the nature of the ion,the nanoclay may be rendered hydrophobic or hydrophilic. The nanoclaythat is used in the present disclosure may be at least any one selectedfrom the group consisting of: hydrophilic nanoclay organically modifiedby substitution with an alkyl ammonium or alkyl phosphonium ion treatedwith a Na ion, a Ca⁺⁺ ion or an acid or having an end hydroxyl group(—OH), in the interlayer space thereof; hydrophobic nanoclay organicallymodified by substitution with a hydrophobic alkyl ammonium or alkylphosphonium ion; and a combination of the hydrophilic nanoclay and thehydrophobic nanoclay.

The nanoclay may be used in combination with carbon nanotubes CNTs. Whenthe CNTs are combined with the nanoclay, they have the effects ofincreasing the dispersibility of the nanoclay in the polyol resin andincreasing heat insulation performance by making cells uniform duringfoaming. However, the type and content of the CNTs are not particularlylimited.

Mixing of the nanoclay and the mixture is preferably performed under atemperature of 20 to 40° C. and a stirring speed of 50 to 700 rpm for 30minutes to 3 hours, without being limited thereto.

The mixture solution in step (3) preferably has a viscosity of 5,000 cpsor less. If the viscosity is more than 5,000 cps, a problem may arise inthat the dispersion efficiency in the subsequent dispersion processperformed using ultrasonic waves or high pressure is lowered.

In step (4), ultrasonic waves or high pressure is applied to the mixturesolution of step (3), so that the interlayer space of the nanoclay isexpanded and the mixture is intercalated into the expanded interlayerspace of the nanoclay (FIG. 1B).

At this time, one selected from the group consisting of silane couplingagents and combinations thereof may be added. The silane coupling agentis an organic-inorganic intermediate that acts to facilitateintercalation of the mixture into the expanded layer space of thenanoclay by overcoming the incompatibility between the mixture havingorganic properties and the nanoclay having inorganic properties. Inaddition, the silane coupling agent may be mixed in advance in step (3).However, in the present disclosure, the content of the silane couplingagent is not limited.

The silane coupling agent may be at least any one selected from thegroup consisting of aminopropyltrimethoxysilane,3-(2-aminoethyl)aminopropylmethyldimethoxysilane,(3-trimethoxysilylpropyl)diethyleneamine,bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane,glycidoxypropyltrimethoxysilane, and bis(trimethoxysilyl)ethane.

After the preparation of the mixed solution is completed, application ofultrasonic waves or high pressure is performed.

The intensity of ultrasonic waves for dispersing the mixture into theinterlayer space of the nanoclay through dispersion is preferably 200 to3,000 W at 20 kHZ. If the intensity is lower than 200 W, the efficiencyof dispersion is lowered, and if the intensity is higher than 3,000 W, aproblem arises in that physical properties are degraded due to damage tothe nanoclay. The flow rate of the mixture solution to which ultrasonicwaves may be applied may be 100 ml/min to 20 L/min without being limitedthereto, and may be controlled depending on the intensity of theultrasonic waves for dispersion. When ultrasonic waves are applied, thetemperature of the nanoclay and the polyol-based compound may increasedue to vibration and friction. Thus, the temperature is preferablycontrolled at 15 to 80° C. If the temperature is lower than 15° C., aproblem arises in that the efficiency of dispersion is lowered, and ifthe temperature is higher than 80° C., a problem arises in that aportion of the components is undesirably vaporized.

High pressure for intercalating the mixture into the interlayer space ofthe nanoclay through dispersion is applied through a high-pressurehomogenizer. The high-pressure homogenizer is a system that inducesdispersion of a fluid in a chamber having a certain size by applyinghigh pressure to the fluid. In the present disclosure, a high pressureof 1000 to 3,000 bar is applied through the high-pressure homogenizer.If the high pressure is lower than 1,000 bar, the efficiency ofdispersion is lowered, resulting in degradation in physical properties,and if the high pressure is higher than 3,000 bar, physical propertiesare degraded due to damage to the nanoclay. The smooth intercalation ofthe components of the mixture into the interlayer space of the nanoclaylayers may be confirmed through measurement of physical properties.

Assuming that the distance of interlayer spacing of naturally occurringor organically modified nanoclay is d, expansion of the interlayer spaceof the nanoclay occurs due to vibration, shock, or pressure duringapplication of ultrasonic waves or high pressure, and at this time, thecomponents of the mixture are intercalated into the expanded interlayerspace of the nanoclay. After completion of the intercalation of themixture into the interlayer space of the nanoclay, aggregation betweenthe nanoclay layers does not occur even if ultrasonic waves are nolonger applied. Assuming that the distance of interlayer spacing of thenanoclay after the application of ultrasonic waves or high pressure asdescribed above is d′, d′ is greater than d (d<d′), which indicates thatthe interlayer space of the nanoclay has been expanded.

In step (5), a foaming agent is added. If the foaming agent is addedprior to the dispersion process performed using ultrasonic waves or highpressure, a problem arises in that the foaming agent is vaporized byheat due to vibration and friction or pressure. The step of adding thefoaming agent is preferably performed at a temperature below the boilingpoint of the foaming agent. If the temperature is higher than theboiling temperature of the foaming agent, a problem may also arise inthat the foaming agent is vaporized. The foaming agent is preferably amaterial having low thermal conductivity and high stability.Specifically, the foaming agent may be at least any one selected fromthe group consisting of cyclopentane, chlorofluorocarbon, isopentane,n-pentane, hydrochlorofluorocarbon, hydrofluorocarbon, and water.

In step (6), an isocyanate-based compound is added. After theisocyanate-based compound is added and mixed, the resulting mixture maybe injected into a mold having a certain size in a high-pressure foamingmachine or a low-pressure foaming machine, or may be sprayed onto anadherend surface through a mixing gun. A foaming system may includevarious systems such as Graco, Gusmer, and Gras-craft. While a dischargepressure of 50 to 200 bar and a temperature 30 to 70° C. are maintained,the polyol-based compound and the isocyanate-based compound may beactivated chemically according to a mechanism caused by collision andmixing thereof and may be sprayed.

The isocyanate-based compound may be, but is not particularly limitedto, at least one selected from among m-MDI (monomeric-methylenediisocyanate), p-MDI (polymeric-methylene diisocyanate), TDI (toluenediisocyanate), derivatives thereof or mixtures thereof.

When the isocyanate-based compound moves to the polyol-based compoundintercalated into the interlayer space of the nanoclay, an in-situ chainreaction occurs in which a urethane reaction, a urea reaction and anisocyanurate reaction caused by the trimerization catalystsimultaneously occur as shown in FIG. 3 (FIG. 1C). The in-situ chainreaction is step (7) of the present disclosure.

The ratio of the weight of the isocyanate-based compound, which is addedin step (6), relative to the weight of the mixture resulting from step(5), is 0.65 to 3.0. If the ratio of the weight is less than 0.65 ormore than 3.0, a problem arises in that physical properties such asstrength or flame retardancy are degraded rapidly.

In step (8), the produced urethane structure, urea structure andisocyanurate structure contribute to complete exfoliation of thenanoclay layers by further expanding the distance of expanded interlayerspace of the nanoclay through rapid increases in the molecular weightand volume of the reaction product formed in the interlayer space (FIG.1D).

The thermosetting foam produced as described above has a density of 35kg/m³ to 40 kg/m³ while having excellent flame retardancy. After aspecimen of the thermosetting foam is burned for 5 minutes according toan ISO 5660-1 test method, the specimen is increased in height by 3 mmto 10 mm due to expansion of char, and the total weight loss thereofdoes not exceed 5.0 g to 6.5 g while the expanded state of the char thatincreased in height is maintained. The volume of conventional foamgenerally decreases after burning, but the thermosetting foamed foam ofthe present disclosure expands in volume during burning, and thus may bemaintained in an airtight state, thereby exhibiting better flameretardant performance. Furthermore, the polyurethane foam itself hasvery excellent flame retardancy and semi-non-flammable performance, evenwhen an additional material that improves flame retardancy, such as aniron plate or a silver foil, is not attached to the outer surface of thepolyurethane foam.

However, if the nanoclay is not completely dispersed in the mixture,unlike the present disclosure, the density of the thermosetting foam mayexceed 40 kg/m³. In addition, after a specimen of the thermosetting foamis burned for 5 minutes according to an ISO 5660-1 test method, thespecimen does not increase in height by 3 mm or more, and the totalweight loss thereof exceeds 6.5 g.

The thermoplastic foam produced according to the present disclosure maybe hard, soft or semi-hard foam having a density of 40 kg/m³ or less.

For the thermosetting foam produced as described above, an exfoliatedstate obtained by expanding the distance of interlayer space of thenanoclay could be analyzed using an X-ray diffraction analyzer, and theresults of the analysis are shown in FIG. 2 . The distance of interlayerspacing of the nanoclay may be calculated by the Bragg's law equationusing the non-expanded interlayer spacing of the nanoclay as areference. The foam produced using the solution dispersion method isindicated as curve 1 in FIG. 2 , and the foam produced using theultrasonic dispersion method is indicated as curve 2 in FIG. 2 .

2dsinθ=nλ (Bragg's law)

wherein d: distance between crystal planes (nanoclay layers), θ: anglebetween incident X-ray and crystal plane, and X,: X-ray wavelength

In general, the 2 θ value of the X-ray diffraction peak represents theinterlayer spacing of the nanoclay. As the 2 θ value decreases, theinterlayer spacing increases, and when complete exfoliation occurs, thepeak disappears. Thus, it can be seen through FIG. 2 that, in theproduction of the thermosetting foam according to the presentdisclosure, the components of the mixture were first intercalatedbetween the nanoclay layers by an ultrasonic dispersion method, and thenanoclay layers were completely exfoliated during the in-situ chainreaction performed using the trimerization catalyst and theisocyanate-based compound.

The mechanism of burning of the thermosetting foam is shown in FIG. 4 .As shown therein, nanoclay is dispersed as lamellae and serves as abarrier that blocks flame and heat during burning. When burning starts,char is formed on the surface of the foam. At this time, the generatedgas and water are trapped by the nanoclay, and the amount of gas andwater generated further increases over time. Eventually, a phenomenonappears in which the char expands. The flame is extinguished, and theexpanded char increases in height by 3 mm or more while maximizing theheat shielding effect. Finally, the flame retardancy is furtherincreased, and the final weight loss measured by the test method is 6.5g or less.

Hereinafter, the present disclosure will be described in detail withreference to specific examples and comparative examples. These examplesserve merely to illustrate the present disclosure, and should not beconstrued as limiting the scope of the present disclosure.

Table 1 below shows the composition ratio and dispersion method used ineach example, and Tables 2 and 3 below show the composition ratio anddispersion method used in each comparative example.

Example 1

For production of a polyol-based compound containing nanoclay, 80 wt %of a polyester polyol, 20 wt % of a polyether polyol, 1.5 wt % of water,0.7 wt % of a surfactant, 20 wt % of a phosphorus-based flame retardant,0.15 wt % of a catalyst, 2.3 wt % of a trimerization catalyst, and 3 wt% of nanoclay were introduced and stirred under the conditions of 25° C.and 150 rpm for 30 min. After completion of the stirring, the solutionwas passed through a continuous ultrasonic system at a flow rate of 6L/min while the nanoclay was dispersed by applying ultrasonic waveshaving an intensity of 1,500 W at a frequency of 20 kHz, and thesolution was discharged. To the polyol-based compound in which thenanoclay was completely dispersed, 15 wt % of a foaming agent(HCFC-141B) was added, and the mixture was stirred at 100 rpm for 10minutes and placed in container B of a foaming machine. Anisocyanate-based compound was placed in container A of the foamingmachine. The solutions in containers A and B of the foaming machine weredischarged into a mold at a ratio of 120:100 (A:B), thereby producingthermosetting foam. At this time, the temperature of the solutions incontainers A and B was 50° C., and the discharge pressure was 100 bar.

Example 2

Thermosetting foam was produced in the same manner as in Example 1,except that the nanoclay was used in an amount of 5 wt %.

Example 3

Thermosetting foam was produced in the same manner as in Example 2,except that the trimerization catalyst was excluded from the compositionof Example 2, the isocyanurate compound was added in an amount of 3 wt%, and the ratio of the solutions in containers A and B of the foamingmachine was 100:100.

Example 4

Thermosetting foam was produced in the same manner as in Example 2,except that the isocyanurate compound in the composition of Example 2was added in an amount of 3 wt %.

Example 5

Thermosetting foam was produced in the same manner as in Example 1,except that the polyol-based compound containing nanoclay was dispersedat a high pressure of 1,500 bar in a high-pressure homogenizer insteadof the ultrasonic dispersion method.

Example 6

Thermosetting foam was produced in the same manner as in Example 2,except that the polyol-based compound containing nanoclay was dispersedat a high pressure of 1,500 bar in a high-pressure homogenizer insteadof the ultrasonic dispersion method.

Example 7

For production of a polyol-based compound containing nanoclay, 80 wt %of a polyester polyol, 20 wt % of a polyether polyol, 1 wt % of water,1.2 wt % of a surfactant, 20 wt % of a phosphorus-based flame retardant,0.7 wt % of a catalyst, 3.8 wt % of a trimerization catalyst, and 3 wt %of nanoclay were introduced and stirred under the conditions of 25° C.and 150 rpm for 30 min. After completion of the stirring, the solutionwas passed through a continuous ultrasonic system at a flow rate of 6L/min while the nanoclay was dispersed by applying ultrasonic waves withan intensity of 1,500 W at a frequency of 20 kHz, and the solution wasdischarged. To the polyol-based compound in which the nanoclay wascompletely dispersed, 23 wt % of a foaming agent (HCFC-141B) was added,and the mixture was stirred at 100 rpm for 10 minutes and placed incontainer B of a foaming machine. An isocyanate-based compound wasplaced in container A of the foaming machine. The solutions incontainers A and B of the foaming machine were discharged into a mold ata ratio of 200:100 (A:B), thereby producing thermosetting foam. At thistime, the temperature of the solutions in containers A and B was 50° C.,and the discharge pressure was 100 bar.

Example 8

Thermosetting foam was produced in the same manner as in Example 7,except that the nanoclay was used in an amount of 5 wt %.

Comparative Example 1

For production of a polyol-based compound containing nanoclay, 80 wt %of a polyester polyol, 20 wt % of a polyether polyol, 1.5 wt % of water,0.7 wt % of a surfactant, 20 wt % of a phosphorus-based flame retardant,0.15 wt % of a catalyst, 2.3 wt % of a trimerization catalyst, and 3 wt% of nanoclay were introduced and stirred under the conditions of 25° C.and 150 rpm for 30 min. After completion of the stirring, the solutionwas stirred with a high-speed stirrer at 500 rpm for 10 minutes anddischarged. To the polyol-based compound in which the nanoclay wascompletely dispersed, 15 wt % of a foaming agent (HCFC-141B) was added,and the mixture was stirred at 100 rpm for 10 minutes and placed incontainer B of a foaming machine. An isocyanate-based compound wasplaced in container A of the foaming machine. The solutions incontainers A and B of the foaming machine were discharged into a mold ata ratio of 120:100 (A:B), thereby producing thermosetting foam. At thistime, the temperature of the solutions in containers A and B was 50° C.,and the discharge pressure was 100 bar.

Comparative Example 2

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that dispersion of the polyol-based compoundcontaining nanoclay was performed with a high-speed stirrer at 5,000 rpmfor 10 minutes.

Comparative Example 3

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that dispersion of the polyol-based compoundcontaining nanoclay was performed with a high-speed stirrer at 5,000 rpmfor 30 minutes.

Comparative Example 4

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that dispersion of the polyol-based compoundcontaining nanoclay was performed with a high-speed stirrer at 8,000 rpmfor 30 minutes.

Comparative Example 5

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that a solution containing no nanoclay in thecomposition of the polyol-based compound of Comparative Example 1 wasprepared, and separate dispersion was not performed because the solutioncontained no nanoclay.

Comparative Example 6

For production of a polyol-based compound, 80 wt % of a polyesterpolyol, 20 wt % of a polyether polyol, 1 wt % of water, 1.2 wt % of asurfactant, 20 wt % of a phosphorus-based flame retardant, 0.7 wt % of acatalyst, and 3.8 wt % of a trimerization catalyst were introduced andstirred under the conditions of 25° C. and 150 rpm for 30 min.Thereafter, 23 wt % of a foaming agent (HCFC-141B) was added to thepolyol-based compound, and the mixture solution was stirred at 100 rpmfor 10 minutes and placed in container B of a foaming machine. Anisocyanate-based compound was placed in container A of the foamingmachine. The solutions in containers A and B of the foaming machine weredischarged into a mold at a ratio of 200:100 (A:B), thereby producingthermosetting foam. At this time, the temperature of the solutions incontainers A and B was 50° C., and the discharge pressure was 100 bar.

Comparative Example 7

For production of a polyol-based compound, 80 wt % of a polyesterpolyol, 20 wt % of a polyether polyol, 1 wt % of water, 1.2 wt % of asurfactant, 20 wt % of a phosphorus-based flame retardant, 0.7 wt % of acatalyst, and 3.8 wt % of a trimerization catalyst were introduced andstirred under the conditions of 25° C. and 150 rpm for 30 min.Thereafter, 23 wt % of a foaming agent (HCFC-141B) was added to thepolyol-based compound, and the mixture solution was stirred at 100 rpmfor 10 minutes and placed in container B of a foaming machine. Anisocyanate-based compound was placed in container A of the foamingmachine. Here, the isocyanate-based compound contained 5 wt % ofnanoclay, and the mixture solution containing the same was stirred witha high-speed stirrer at 5,000 rpm for 10 minutes. The solutions incontainers A and B of the foaming machine were discharged into a mold ata ratio of 200:100 (A:B), thereby producing thermosetting foam. At thistime, the temperature of the solutions in containers A and B was 50° C.,and the discharge pressure was 100 bar.

Comparative Example 8

Thermosetting foam was produced in the same manner as in ComparativeExample 7, except that the mixture solution containing theisocyanate-based compound containing 5 wt % of nanoclay in ComparativeExample 7 was stirred with a high-speed stirrer at 5,000 rpm for 30minutes.

Comparative Example 9

Thermosetting foam was produced in the same manner as in ComparativeExample 7, except that the mixture solution containing theisocyanate-based compound containing 5 wt % of nanoclay in ComparativeExample 7 was stirred with a high-speed stirrer at 10,000 rpm for 30minutes.

Comparative Example 10

Thermosetting foam was produced in the same manner as in ComparativeExample 7, except that the mixture solution containing theisocyanate-based compound containing 5 wt % of nanoclay in ComparativeExample 7 was passed through a continuous ultrasonic system at a flowrate of 6 L/min while the nanoclay was dispersed by applying ultrasonicwaves having an intensity of 1,500 W at a frequency of 20 kHz.

Comparative Example 11

Thermosetting foam was produced in the same manner as in ComparativeExample 7, except that the mixture solution containing the polyol-basedcompound and the isocyanate-based compound, each containing 2.5 wt % ofnanoclay, in Comparative Example 7, was passed through a continuousultrasonic system at a flow rate of 6 L/min while the nanoclay wasdispersed by applying ultrasonic waves having an intensity of 1,500 W ata frequency of 20 kHz.

Comparative Example 12

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that the trimerization catalyst was excluded from thecomposition of the polyol-based compound of Comparative Example 1.

Comparative Example 13

Thermosetting foam was produced in the same manner as in ComparativeExample 1, except that the composition of the polyol-based compound ofComparative Example 1 contained 3 wt % of an inorganic expansion agentinstead of the nanoclay.

Comparative Example 14

Thermosetting foam was produced in the same manner as in ComparativeExample 5, except that the composition of the polyol-based compound ofComparative Example 5 contained 3 wt % of an inorganic expansion agentinstead of the nanoclay.

Comparative Example 15

Thermosetting foam was produced in the same manner as in ComparativeExample 5, except that the composition of the polyol-based compound ofComparative Example 5 contained 3 wt % of an organic expansion agentinstead of the nanoclay.

TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple3 ple 4 ple 5 ple 6 ple 7 ple 8 Compo- Polyol- Polyester 80 80 80 80 8080 80 80 sition based polyol compound Polyether 20 20 20 20 20 20 20 20(containing polyol foaming Water 1.5 1.5 1.5 1.5 1.5 1.5 1 1 agent andFoaming 15 15 15 15 15 15 23 23 nanoclay) agent (HCFC141B) Surfactant0.7 0.7 0.7 0.7 0.7 0.7 1.2 1.2 Phosphorus 20 20 20 20 20 20 20 20 basedflame retardant Catalyst 0.15 0.15 0.15 0.15 0.15 0.15 0.7 0.7Trimerization 2.3 2.3 0 2.3 2.3 2.3 3.8 3.8 catalyst Isocyanurate 0 0 33 0 0 0 0 Nanocaly 3 5 5 5 3 5 3 5 Mixing ratio of 120 120 100 120 120120 200 200 isocyanurate-based compound (relative to 100 wt % ofpolyol-based compound containing foaming agent and nanoclay) Method fordispersing nanoclay Ultrasonic Ultrasonic Ultrasonic Ultrasonic HighHigh Ultrasonic Ultrasonic pressure pressure dispersion dispersion

TABLE 2 .Compar- .Compar- .Compar- .Compar- .Compar- .Compar- .Compar-ative ative ative ative ative ative ative Exam- Exam- Exam- Exam- Exam-Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 Compo- Polyol-Polyester 80 80 80 80 80 80 80 sition based polyol compound Polyether 2020 20 20 20 20 20 (containing polyol foaming Water 1.5 1.5 1.5 1.5 1.5 11.5 agent and Foaming agent 15 15 15 15 15 23 15 nanoclay) (HCFC141B)Surfactant 0.7 0.7 0.7 0.7 0.7 1.2 0.7 Phosphorus 20 20 20 20 20 20 20based flame retardant Catalyst 0.15 0.15 0.15 0.15 0.15 0.7 0.15Trimerization 2.3 2.3 2.3 2.3 2.3 3.8 2.3 catalyst Isocyanurate 0 0 0 00 0 0 Nanocaly 5 5 5 5 0 0 0 Mixing ratio of 120 120 120 120 120 200 120isocyanurate-based compound (relative to 100 wt % of polyol-basedcompound containing foaming agent and nanoclay) Nanoclay (dispersion ofnanoclay 0 0 0 0 0 0 5 mixed with isocyanurate based compound) Methodfor dispersing nanoclay Solution Solution Solution Solution — — Solutiondispersion dispersion dispersion dispersion dispersion 500 5,000 5,00010,000 5,000 RPM_10 RPM_10 RPM_30 RPM_30 RPM_10 min min min min min

TABLE 3 Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar-ative ative ative ative ative ative ative ative Exam- Exam- Exam- Exam-Exam- Exam- Exam- Exam- ple 8 ple 9 ple 10 ple 11 ple 12 ple 13 ple 14ple 15 Compo- Polyol- Polyester 80 80 80 80 80 80 80 80 sition basedpolyol compound Polyether 20 20 20 20 20 20 20 20 (containing polyolfoaming Water 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 agent and Foaming agent 1515 15 15 15 15 15 15 nanoclay) (HCFC141B) Surfactant 0.7 0.7 0.7 0.7 0.70.7 0.7 0.7 Phosphorus 20 20 20 20 20 20 20 20 based flame retardantCatalyst 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Trimerization 2.3 2.32.3 2.3 0 2.3 2.3 2.3 catalyst Isocyanurate 0 0 0 0 0 0 0 0 Nanocaly 0 00 2.5 5 3 (inorganic 3 (inorganic 3 (inorganic expansion expansionexpansion agent) agent) agent) Mixing ratio of 120 120 120 120 100 120120 120 isocyanurate-based compound (relative to 100 wt % ofpolyol-based compound containing foaming agent and nanoclay) Nanoclay(dispersion of nanoclay 5 5 5 2.5 0 0 0 0 mixed with isocyanurate basedcompound) Method for dispersing nanoclay Solution Solution UltrasonicUltrasonic Ultrasonic Ultrasonic — — dispersion dispersion 5,000 10,000RPM_30 RPM_30 min min

Test 1

The densities of the thermosetting foams of the Examples according tothe present disclosure and the Comparative Examples were measuredaccording to ISO 845.

Test 2

The self-extinguishing time and weight loss of each of the thermosettingfoams of the Examples according to the present disclosure and theComparative Examples were measured according to an ISO 5660-1 burningtest. For measurement of the weight loss, the weight loss of eachspecimen after 5 minutes of burning compared to before the burning testwas measured. The specimen size was 100*100*50T, and each specimen wascomposed of only a single material without including a cotton material.

Test 3

The thermal conductivity of each of the thermosetting foams of theExamples according to the present disclosure and the ComparativeExamples was measured according to ASTM C 518.

Test 4

The increase in height after burning of each of the thermosetting foamsof the Examples according to the present disclosure and the ComparativeExamples was measured as follows. In addition, the shapes of thesethermosetting foams before and after burning can be seen in FIG. 4 andTables 4 to 9 below.

Increase (mm) in height after burning=specimen height (mm) afterburning−specimen height (mm) before burning

Tables 4 and 5 below are photographs showing the change in height byexpansion after burning compared to before burning of each of thethermosetting foams of Examples 1 to 8, and Tables 6 to 9 below arephotographs showing the change in height by expansion after burning 20compared to before burning of each of the thermosetting foams ofComparative Examples 1 to 15.

Table 10 shows test results for Examples 1 to 8, and Tables 11 and 12below show test results for Comparative Examples 1 to 15.

TABLE 10 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple3 ple 4 ple 5 ple 6 ple 7 ple 8 Density 35 35 37 36 38 38 37 37 (kg/m³)Self- 00:21 00:15 00:38 00:33 00:42 00:38 00:48 00:43 extinguishing time(min:sec) Weight 5.8 5.4 6.0 5.7 6.1 5.9 6.2 6.1 loss (g) Thermal 0.02040.0201 0.0206 0.0207 0.0212 0.0212 0.0215 0.0215 conductivity (W/mK)Increase 9.50 9.51 4.34 9.10 4.01 4.04 4.17 4.54 (mm) in height afterburning

TABLE 11 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Exam- Exam-Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6ple 7 ple 8 Density 49 47 47 46 36 41 47 44 (kg/m³) Self- 4:36 4:17 3:413:55 x 4:41 3:45 3:02 extinguishing time (min:sec) Weight 8.8 8.5 7.77.7 10.5 8.9 7.9 7.4 loss (g) Thermal 0.0238 0.0227 0.0231 0.0235 0.02050.0228 0.0229 0.0231 conductivity (W/mK) Increase −5.21 −1.30 1.33 2.74−7.08 −3.81 −3.55 −3.10 (mm) in height after burning

TABLE 12 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Exam- Exam- Exam-Exam- Exam- Exam- Exam- ple 9 ple 10 ple 11 ple 12 ple 13 ple 14 ple 15Density 41 41 38 47 48 49 45 (kg/m³) Self- 2:48 2:53 1:49 x x x xextinguishing time (min:sec) Weight 7.1 7.2 6.7 10.7 8.8 8.1 10.2 loss(g) Thermal 0.0234 0.0230 0.0222 0.0230 0.0245 0.0249 0.0237conductivity (W/mK) Increase −1.90 −1.81 −0.93 −26.21 −3.16 −3.00 Not(mm) in measurable height after burning

Even though the thermosetting foams of the Examples of the presentdisclosure contained nanoclay, the densities thereof did not increasecompared to those of the thermosetting foams of the Comparative Examplesthat contained no nanoclay. However, the thermosetting foams of theExamples of the present disclosure showed significantly improved flameretardant performance while the weight losses thereof after burning didnot exceed 6.5 g, indicating complete dispersion of the nanoclay, thecomplete intercalation of the components of the thermosetting foam intothe interlayer space of the nanoclay, and the exfoliation of thenanoclay. This may be evidenced by the increased height after burning.The well-dispersed nanoclay is layered between the materialsconstituting the thermosetting foam and serves as a barrier. When thematerials start to burn, char is formed on the surface, and at thistime, the generated gas and water are trapped by the nanoclay layers,and the amount of gas and water generated further increases over time.Eventually, a phenomenon appears in which the char expands. The flame isextinguished, and the expanded char increases in height by 3 mm or morewhile maximizing the heat shielding effect, and the phenomenon remainsthe same. Finally, the flame retardant performance significantlyincreases. However, if the isocyanurate structure realized by thetrimerization catalyst or the isocyanurate compound, among thestructures constituting the thermosetting foam, is not formed, a problemarises in that the above-described flame retardant performance cannot berealized only by dispersion of the nanoclay. Finally, when thethermosetting foam was produced using the expansion agent instead of thenanoclay and tested, it expanded temporarily at the beginning of theburning test, but a problem arose in that the thermosetting foam shrunkor melted without enduring a continuous flame, resulting indeterioration in the flame retardant performance.

1. A thermosetting expanded foam having an excellent flame retardancywhich is obtained by curing an expanded foam solution with anisocyanate-based compound as a curing agent, and which is increased inheight by 3 mm or more due to expansion of char and has a total weightloss of 6.5 g or less, after 5 minutes of burning according to an ISO5660-1 burning test.
 2. The thermosetting expanded foam of claim 1,wherein the isocyanate-based compound is selected from among m-MDI(monomeric-methylene diisocyanate), p-MDI (polymeric-methylenediisocyanate), TDI (toluene diisocyanate), derivatives thereof ormixtures thereof.
 3. The thermosetting expanded foam of claim 1, whereina ratio of a weight of the isocyanate-based compound relative to thethermosetting foam having excellent flame retardancy according to claim1 is 0.65 to 3.0.
 4. The thermosetting expanded foam of claim 1,comprising a density of 40 kg/m³ or less, a weight loss of 6.5 g orless, and a thermal conductivity of 0.022 W/mK or less.
 5. A method formaking a thermosetting expanded foam having an excellent flameretardancy, the method comprising: curing an expanded foam solution withan isocyanate-based compound as a curing agent, wherein thethermosetting expanded foam is increased in height by 3 mm or more dueto expansion of char and has a total weight loss of 6.5 g or less, after5 minutes of burning according to an ISO 5660-1 burning test.
 6. Themethod of claim 5, wherein the isocyanate-based compound is selectedfrom among m-MDI (monomeric-methylene diisocyanate), p-MDI(polymeric-methylene diisocyanate), TDI (toluene diisocyanate),derivatives thereof or mixtures thereof.
 7. The method of claim 5,wherein a ratio of weight of the isocyanate-based compound relative tothe thermosetting foam is 0.65 to 3.0.
 8. The method of claim 5, whereinthe thermosetting expanded foam comprises a density of 40 kg/m³ or less,a weight loss of 6.5 g or less, and a thermal conductivity of 0.022 W/mKor less.